JAIC 1996, Volume 35, Number 1, Article 5 (pp. 61 to 73)
JAIC online
Journal of the American Institute for Conservation
JAIC 1996, Volume 35, Number 1, Article 5 (pp. 61 to 73)


Leslie Carlyle, Robert L. Feller, Paul Jett, Norman E. Muller, Mary Clerkin Higgins, & Mark H. McCormick-Goodhart


ASHOKROY, EDITOR. ARTISTS' PIGMENTS: A HANDBOOK OF THEIR HISTORY AND CHARACTERISTICS, VOLUME 2Washington, D.C.: National Gallery of Art; New York: Oxford University Press, 1994. 230 pages. $49.95. Available from Oxford University Press (800) 451–7556. ISBN 0-89468-189-3.

Volume 2 in the Artists' Pigments Series consists of nine monographs on pigments that first appeared in Studies in Conservation between 1966 and 1974 and that formed the initial concept for a series on pigments (volume 1 was published in 1986). Through the editorship of Ashok Roy, head of the Scientific Department, National Gallery, London, volume 2 is much more than a simple compilation of the original series of articles in Studies in Conservation. Dr. Roy has made excellent use of the resources of the National Gallery, London, by including new information contributed from both the scientific and the conservation sections. His own extensive experience and broad knowledge of the field are reflected not only in the contributions he was able to make from his own work but also in the number of new references he has included from work by international colleagues.

Volume 2 covers the following pigments: azurite and blue verditer; ultramarine blue, natural and artificial; lead white; lead-tin yellow; smalt; verdigris and copper resinate; vermilion and cinnabar; malachite and green verditer; and calcium carbonate whites. They are organized according to the original order of the monographs rather than grouped by color or composition.

Each pigment chapter is divided into roughly similar sections that include information on nomenclature (current and obsolete terms); chemical composition and properties; history (of manufacture and use); preparation; and methods of identification using particle characteristics, optical properties, microchemical tests, and instrumental analyses. Where applicable, there is a subsection on terminal dates. Each chapter closes with a list of notable occurrences (a positive identification of the pigment in a specific art work of known date and attribution).

Chapters contain more or less detail under each of the various headings described above, and some include other subheadings specific to that chapter. In fact the subheadings are not identical throughout. For example the chapter on vermilion contains a section on “Substitution and Sophistication,” but there is no corresponding section in the chapter on natural ultramarine, although the authors do note that, in the past, warnings against adulteration and even counterfeited ultramarine were common (p. 41).

Generally, the information is more uniform and consistent in the sections covering particle characteristics, optical properties, microchemical tests, and instrumental analyses. Authors' contributions vary more in the sections relating to the history of manufacture and use. The chapter by Joyce Plesters on ultramarine blue and the chapters by Hermann Kühn are particularly comprehensive in these latter categories.

All the pigment chapters have been thoroughly edited and enriched with new information by Ashok Roy. In some cases, such as the chapters covering azurite and blue verditer, lead-tin yellow, smalt, and copper resinate, the additions and updates are substantial. Of particular interest to the conservator are the additions in the chapters on blue pigments from Sarah Staniforth's work determining which alternative pigments make the best match (metamerically) for retouching.

Information on methods of instrumental analyses have been updated and include technology developed since the monographs were published originally. References at the end of each chapter contain new citations; in some, there are up to 26 new references. Throughout, the sections on notable occurrences have been augmented.

Another improvement is in the color reproductions. Although the same reproductions that appeared in Studies in Conservation have been used, their quality has been significantly enhanced. New color reproductions, graphs, and new scanning electron micrographs also add valuable information. The layout of the text and illustrations has been greatly improved, making the articles easier to read.

The Artists' Pigments Series as a whole represents an extremely valuable resource for conservation scientists and conservators in particular since it seeks to present the most up-to-date and comprehensive information available. Unlike other more general sources on pigments, the information is particularly focused to the interests and needs of researchers and practitioners in the field of conservation.

If there is any fault to be found in the Artists' Pigments Series, it is that it suffers slightly from a strong scientific focus, which does not do sufficient duty to “artistical” information on pigments. When the well-known British colormaker George Field wrote his book on artists' pigments in 1835, he focused on pigments as chemical entities but also gave almost equal attention to their “powers in painting.” Thus he included pigment characteristics important to the artist, such as transparency, drying quality, and ease of manipulation. He reported not only on their lightfastness but also on whether the color shifted in hue and whether it was incompatible with other pigments or with certain media.

Throughout volume 2 this kind of information is sometimes presented, and indeed the subheadings “Permanence” or “Permanence and Compatibility” are included in each chapter. However, handling qualities, drying characteristics, transparency, and workability are not given separate subheadings, and this information is much less easily accessible or consist-ently reported than the information strictly oriented toward pigment identification. Aside from being useful in the interpretation of paintings, such information would make the pigment series more truly applicable to the whole of the audience it advertises to serve: artists, art historians, curators, and connoisseurs as well as conservation scientists and conservators.

Overall, the Artists' Pigment Series provides an invaluable reference source. Volume 2 has been produced to a very high standard and is well worth the investment.

LeslieCarlyleCanadian Conservation Institute, 1030 Innes Road, Ottawa, Ontario, Canada K1A OM5HUGOVERSCHOOR AND JAAPMOSK, EDITORS. CONTRIBUTIONS OF THE CENTRAL RESEARCH LABORATORY TO THE FIELD OF CONSERVATION AND RESTORATION. Amsterdam: Central Research Laboratory for Objects of Art and Science, 1994. 124 pages. Softcover, 1,50 Dutch florins. Available from the Central Research Laboratory, Gabriel Metsustraat 8, 1071 EA, Amsterdam, The Netherlands.

Agnes Gräfin Ballestrem, director of the Central Research Laboratory, states in the preface that this initial English-language offering to colleagues reports on projects and investigations carried out by the laboratory in 1992 and 1993. Nicely turned out in a semigloss paper, the quarter-inch-thick, octavo-sized booklet will find an easy place on the conservator's bookshelf, a thoughtful gesture in contrast to reports that might have been turned out coffee-table-size rather than in a book-shelf– accommodating format. The nine papers here, all well done and useful, clearly illustrate the range of content and author's objectives that one can expect to find in an annual or otherwise periodic report.

Four of the articles present technical studies essentially complete in themselves, accompanied by definite conclusions. The most extensive report, “Research into the Cause of Browning of Papers Mounted in Mats” (by Judith H. Hofenk de Graaff), is helpfully illustrated with 8 graphs and drawings accompanied by more than 30 references to pertinent literature. The research demonstrates that browning of both high- and low-grade papers exposed in the window opening of a mat is the result of oxidation, a consequence of water evaporation at the paper surface owing to variations in relative humidity. The latter is influenced chiefly by changes in the ambient temperature external to the framed and glazed artifact.

A major “Investigation of the Long-Term Effects of Ethylene Oxide Fumigation and Gamma Irradiation on the Aging of Paper” (Judith H. Hofenk de Graaff and Wilma G. Th. Roelofs), supported by nine references to the literature, shows definitely that five types of papers were not affected either mechanically or chemically upon fumigation and later subjection to wet or dry conditions of thermal aging. On the other hand, radiation treatment for 1 hour to 10 kGy of gamma radiation resulted in an increase of 50–100% in the rate of thermal aging, depending on the type of paper.

An extensive study of the “Exposure of Objects of Art and Science to Light from Electronic Flash-Guns and Photocopiers” (Johan Neevel) compares the number of flashes or copies that could be made before an object would be receive an exposure to ultraviolet radiation equivalent to that resulting from a 1 hour exposure to an incandescent lamplight at 50 lux (UV irradiance of 3.75 mW/m2). Seventeen electronic flashguns and 14 photocopiers of different model or manufacturer were tested. Without making a rigorous analysis of the data, one can suggest that the results point to about 10 to 40 exposures permissible on this basis. Five examples indicated that, with some equipment, as much as 153 to 430 exposures would comply with this criterion. Degrees of physical or chemical damage were not measured in this approach to the problem. The value of having such information (initially contained in two internal reports, 1991–92 in Dutch) more widely available is illustrated by the fact that Saunders, reporting on the fading that can be caused by flash lamps (National Gallery Technical Bulletin 16[1995]:66–72) was not in a position to cite this related work, which had been going on at much the same time as that in London.

In the fourth rather complete technical study, Pieter Hallebeck reports on “Comparison of the Corrosive Properties of Seven Types of Plywood,” initially using simple tests of pH and the gain in weight of strips of lead metal. All seven plywood samples caused corrosion. Nine references to the literature are cited.

Two papers provide examples of topics that may hold interest to perhaps a more restricted audience. One engineering study on the behavior of a model of the “Temperier” system of temperature control in museums (B.A.H.G. Jütte, Wilfred Copal, and Jacob A. Mosk), found that this system was not as effective for local needs as a central heating system based on circulating low-temperature water. The Temperier system involves heating rooms by means of air ducts in the walls and floors, much as the Roman baths. The other paper, by Wilma G. Th. Roelofs, reports on “Coloured Mordants on a Set of Dutch Marquetry Furniture from the Late 18th Century.” Luteolin and apigenin were found in a green evidently prepared from weld (yellow) and indigo carmine (blue). A red was derived from sandlewood. Spectrophotometric and thin-layer chromatographic methods of analysis are described.

Two contributions tell of ongoing projects. Marja F. J. Peek and Hayo M. de Boer describe a major program, designated TINCL, that has been initiated to index the contents of early Netherlandish texts on artist's techniques, sources rarely known outside the lowlands. A 17th-century text by Jacoba Van Veen illustrates the approach.

Initial studies relating to an “Investigation into the Degradation of Weighted Silk” have been recorded largely in internal reports. An overview of the program (Thea B. Van Oosten) names the three main areas of the investigation: history of the technology, degradation, and process and methods of conservation. The high-performance liquid chromatography (HPLC) method used for amino acid analysis is briefly described.

In addition to reports on completed, proposed, or ongoing research is the thought-provoking commentary offered by Agnes W. Brokerhof and Ifsbrand Hummelen on the “Restoration Ethics of Natural History Collections.” This commentary presents the facts and points of view that one would need to assimilate before undertaking the care and treatment of natural history specimens. On the last pages of the book, a list of 22 recent publications of the Central Research Laboratory is given. Save for three, only the Dutch titles are cited.

As the capabilities for technical studies on conservation-related topics have greatly expanded worldwide, there is a rising danger of serious delays in the utilization of contributions being made in laboratories that carry on their daily activities in languages not broadly mastered, such as Dutch, Polish, Russian, and Japanese. Thus the efforts of major laboratories to provide timely overviews of their activities in French, English, and German is to be applauded. In 1993, the Central Research Laboratory initiated such an annual report entitled “Investigations by the Central Research Laboratory 1993: Research Abstracts”; it contains 40 summaries—19 pages in English, 30 in Dutch. Providing and publishing these translations are neither a simple nor an inexpensive undertaking for the institution or its staff. Nevertheless, a regularly issued report need not be as elaborate as this 1994 effort or as that of the National Gallery, London, now in its 16th volume. The annual reports in typescript from the British Museum Conservation and Research Department have proven to be of great assistance for those engaged in similar lines of research. Let us encourage others to follow suit if even in modest format.

Robert L.FellerCarnegie Mellon Research Institute 4400 Fifth Ave. Pittsburgh, Pa. 15213NICHOLASPENNY. THE MATERIALS OF SCULPTURE. New Haven: Yale University Press, 1993. 318 pages. Hardcover, $45.00.

DENYSHAYNES. THE TECHNIQUE OF GREEK BRONZE STATUARY. Mainz am Rhein: Verlag Philipp van Zabern, 1992. 156 pages. Hardcover, 65 DM.

Two books on sculpture have been published in recent years that stand in marked contrast to each other in style and approach, yet both do admirable service to their subjects. In spite of their differences, both books deal with the materials and techniques of sculpture and so may interest conservators in this field. But conservators may also find rewards in what these books offer beyond the descriptions of the physical attributes of sculpture.

The more recent of the two books is The Materials of Sculpture by Nicholas Penny. I looked forward to the publication of this work when I first heard of it because I so admired an earlier work by Penny and co-author Francis Haskell entitled Taste and the Antique: The Lure of Classical Sculpture. The Materials of Sculpture, while not as impressive as Taste and the Antique, still provides a most useful and enjoyable survey of the medium of sculpture. As the author states in the introduction, the purpose of such a survey is to aid in the understanding of works of art. So while the book is about materials and techniques, it is not so much technical in its concerns as it is art historical. The discussions of materials focus on how the physical nature of those materials and their manipulation influence the final effect of works of art.

The book is not inclusive in its treatment of sculptural materials. Using sculpture from many periods and cultures as examples, the materials described are wood, ivory, horn, clay, stucco, wax, bronze and other copper alloys, chased metals, and a few types of stone. Modern metal alloys and synthetic materials are not discussed. While most chapters deal with a single material or a small group of closely related materials, some subjects receive lengthier treatments; marble, for example, is the subject of five chapters. One discusses the use of carving tools and techniques to achieve, with greater or lesser success, different sculptural effects; this discussion of marble carving is exemplary of the author's descriptions of how materials are employed.

One of the most useful features of the book, and the most technical in nature, is the glossary. An introductory paragraph for the glossary states that it was not meant to include all materials, tools, and techniques used for sculpture, yet its 20 pages are a rich source of information.

The Materials of Sculpture offers more than superficial treatments in many areas and does so in an appealing way. A clichéd description of the book's production would be to call it “lavish”; the color illustrations are numerous, of excellent quality, and well chosen. Not only does the author very successfully convey a sense of the inherent beauty of sculptural materials; he also gives insightful descriptions of the technical approaches used to make the most of that beauty in the finished work of art.

Where The Materials of Sculpture is large and rich in production, The Technique of Greek Bronze Statuary is small and modest. Whereas the former is broad in topic, the latter is acutely focused. But both books are similar in being erudite and a pleasure to read. In addition, Greek Bronze Statuary was noteworthy for this reader because of the thorough, logical consideration of evidence the author used to reach his conclusions.

The book presents a detailed argument that is meant to define the methods used by the ancient Greeks to manufacture large bronze sculpture. It is divided into 12 short chapters. The first chapter introduces the topic by describing Sphyrelata, the predecessors to large cast sculpture in Greece. Sphyrelata were once believed to have been made by hammering sheet metal over a fully carved wooden core, but the author refutes this theory by describing the technical difficulties (and impossibilities) of such a technique and by demonstrating that these sculptures were made using repoussé methods. Chapter 2 defines four basic methods of casting sculpture: direct lost-wax casting, indirect lost-wax casting, piece mold casting, and casting using a combustible model. The author presents in the next five chapters the physical evidence found on various works of sculpture and from that evidence deduces which of the four possible methods of casting was used. Chapters 8–11 follow the manufacturing process through casting to finishing and coloring; chapter 9 discusses the alloys used in Greek bronze sculpture and provides a compilation of other researchers' previously published analytical results for the elements copper, tin, and lead. The final chapter discusses the Colossus of Rhodes and theories about its making.

Greek Bronze Statuary provides much useful information about alloys, inlays, and construction methods, although it may be that scholars familiar with the art historical details of Greek sculpture will find little new here. More important to this reviewer—what seemed fascinating and even exemplary—was the author's interrogative approach to the examination of physical evidence found on the sculptures. While this book is the work of an art historian (formerly a curator of Greek and Roman art at the British Museum), it demonstrates a methodology that conservators with different specialties might effectively employ in their examinations of objects and their deliberations about the manufacture of those objects.

Greek Bronze Statuary, like some works in the fields of art history and archaeology, occasionally takes on an unnecessarily acerbic tone in its discussions of, and disagreements with, colleagues' works on the same subject. Thankfully, these moments are few, and I believe the reading of this book will be informative and enjoyable for those interested in the subject.

These two books evince a growth in the interest of art historians in the materials and techniques used in the making of art and in the number of studies and publications by them on these topics. The benefits of such publications to conservators are at least twofold. First, they present conservators with new information that may aid their understanding of objects and subsequently improve their work. Second, conservators, with their knowledge of materials and methods, might contribute to future publications of this type and in so doing reach a far greater audience than the specialized literature of conservation allows. Such a confluence of interests between the art historian and the conservator can only be rewarding for both.

PaulJettDepartment of Conservation and Scientific Research, Freer Gallery of Art/Arthur M. Sackler Gallery, Smithsonian Institution, Washington, D.C. 20560ERLING S.SKAUG. PUNCH MARKS FROM GIOTTO TO FRA ANGELICO: ATTRIBUTION, CHRONOLOGY, AND WORKSHOP RELATIONSHIPS IN TUSCAN PANEL PAINTING C.1330–1430. Oslo: IIC—Nordic Group, Norwegian Section, 1994. 600 pages, 2 vols., softcover, 950 Norwegian crowns; hardcover, 1450 NOK. Shipping costs to the U.S. and Canada, 125 NOK. Available from NKF-N, Oslo University Museums, Frederiks gate 3, N-0164 Oslo. ISBN 82-990745-2-5.

This book is an in-depth study of the punch marks found on Florentine panel paintings from 1330 to 1430 and how this information can be used for attribution. The author, a Norwegian art conservator with a doctorate in art history, began this study in the 1960s when he went to Florence after the 1967 flood and fell in love with early Italian painting. Nearly 30 years later we have this impressive two-volume work. It is not simply a dictionary for identifying the punch marks on unknown or misattributed paintings but also a primary source on the known Florentine 14th-century artists and a technical source on halo tooling and the early Italian Renaissance workshop. Although clearly written for the student of early Italian painting who is familiar with the artists the author covers, the book will also be of interest to the art conservator; it is, after all, a study of technique based on years of research and wide-ranging art historical reading.

Twenty years ago, this reviewer had the pleasure of meeting the author in Florence when we were undertaking research in separate areas of early Italian painting. Since then, the reviewer has helped the author secure photographs and through correspondence has discussed problems relating to Sienese 14th-century painting. A section of the author's text devoted to Sienese painting (volume 1, chapter 7, pp. 216–56) explains the transfer of Sienese punch tools to Florence after the recurrence of the plague in 1363.

Volume 1 is divided into three parts. Part 1 introduces the divergent interests and methodologies of the art conservator and art historian and discusses the common ground between them. Skaug is aware of how the two professions look at objects. Knowing that many art historians and others with little grounding in science are uneasy about technical matters, he deliberately has sought to present his data in an easily understandable and accessible manner. Skaug discusses the methodology and work of Mojmir Frinta (another punch mark specialist, or in Skaug's terminology, a “sphragiographer”), his own research, and the work of others in the field. Part 1 concludes with a discussion of the place of gold tooling in the overall construction of panel painting and how the punch tools themselves were made.

Part 2, nearly 250 pages long, forms the core of volume 1. In this section Skaug provides an overview of the development of halo tooling in the century before its introduction in Florence around 1330. He then discusses the artists whose punchwork was studied. This section is a complete reevaluation of each artist's work and career in light of the information derived from halo tooling. The paintings by each artist are listed, followed by sections on attribution, chronology, and workshop relationships. The accompanying footnotes are a rich source of information in themselves. New important hypotheses are raised, particularly on two artists active in both Florence and Siena: Giovanni da Milano, a Florentine, and Bartolomeo Bulgarini, a Sienese.

Giovanni da Milano was registered in the Florentine artist's guild in the early 1340s, but for 17 years, from 1346 to 1363, his whereabouts are unknown. Art historians have speculated that he went to Pisa, Avignon, and Siena, but when Skaug recognized that Giovanni brought back with him to Florence 28 punch tools from the workshop of Bartolomeo Bulgarini, a Sienese artist, a Sienese sojourn during the 1350s becomes plausible. Skaug's view is gradually gaining acceptance among art historians. For example, a formerly double-sided panel now in the Louvre, showing St. Martin and the Beggar on one side and the Fall of the Rebel Angels on the other, has been attributed by Joseph Polzer to Giovanni's Sienese period using stylistic comparisons and punch mark analysis (“The ‘Master of the Rebel Angels’ Reconsidered,” Art Bulletin 63[1981]): 563–84).

Bartolomeo Bulgarini was the most prominent Sienese artist from the 1348 plague until his death in 1378. The extraordinary number of punch marks associated with his workshop (83 versus 41 for Ambrogio Lorenzetti, for example) and the number of other known Sienese artists who shared them led Skaug to postulate that Bulgarini was the head of a large Sienese compagnia after the Black Death in 1348. This combined workshop was organized immediately following the plague and presumably lasted until 1362 or 1363, when the plague recurred. No record of this loose partnership has been found, and before Skaug observed the pattern of punch-tool borrowing by the artists of this proposed compagnia, no such organization was even contemplated. Attempts to prove this theory stylistically have been extremely difficult. It is hoped that researchers will find ways to confirm Skaug's halo tooling findings.

Readers with a special interest in Sienese 14th-century painting will find the section dealing with Sienese artists tempting but ultimately unsatisfying, as the author himself admits. He has approached Florentine punch work thoroughly and critically, but one senses a greater reliance on the views of art historians for the Sienese section and less confidence with the physical evidence. Even for the artists he covers, the punch information he includes is fragmentary. One hopes that Frinta's forthcoming study on the Sienese punch material will fill in the significant gaps and present the well-formed picture that is sorely needed.

Part 3 constitutes all of volume 2 and consists of charts tracing the appearance of motif punch marks in chronologically listed paintings; photographs and line drawings of the 742 punch marks arranged typologically; comparative photographs; and six appendices. The breadth of Skaug's interest in his subject is no-where more apparent than in the appendices, in which he discusses “Florentine vs. Sienese Halo Style,” “Symmetry vs. Nonsymmetry,” “Artists' Addresses in Florence,” “Brocade Patterns,” “A Set of Punches Once Belonging to Federico Joni,” and “On Signatures, Dates, and Current Classification.” Especially outstanding is appendix 2 on symmetry and nonsymmetry, in which the author has found that in color and halo style, the Florentines favored the symmetrical balance of color combinations and halo style between one side of a painting or altarpiece and the other. Conversely, the Sienese favored asymmetry. The author surmises why this was so, pointing out the symmetrical structures in Florentine literature and the pros and cons of symmetry and nonsymmetry in Florentine philosophical discussions.

While the volumes can be read and enjoyed independently of works of art, they are, after all, meant as an aid for identifying unknown or misattributed paintings. In their logical organization, they make this task quite easy for those with immediate access to works of art, such as curators and conservators. For example, with a small metric ruler, the punch shape on a painting is carefully measured and then compared with the line drawing and photograph in volume 2. The punch shapes are arranged systematically, beginning with the simplest forms, such as circles, and progressing to more complex shapes, such as three- and then four-petaled rosettes. When the punch mark has been identified along with the workshop in which it was mainly used, one can then turn to the chart and the detailed description in volume 1. There is obviously more than one punch motif in the vast majority of paintings, and one should therefore trace the origin of each one to determine from which shop the majority of motifs originated. This examination will provide a clue to the workshop origin of the painting.

Of major interest to both art historians and conservators is the way Skaug has traced the migration of punch tools from artist to artist, either when an artist died or when tools were shared during a commission. This phenomenon was rare before 1348 but became quite common thereafter. Because Skaug concludes that punches were engraved from iron stock and not cast from some other metal, each tool was therefore unique and not replicable. The transfer of tools implied personal contact between artists. Consequently, the discussion of “workshop relationships” is a valuable contribution to the art historical literature, focusing attention on the interconnection between artist's shops. Skaug concludes volume 1 with a chapter on the “workshop concept.” The success or failure of Skaug's thesis rests on how effectively he can convince his readers that late medieval punch tools were engraved and not cast. While this reviewer accepts his conclusions, having reviewed the problem at length, a more thorough presentation of the issue from many different angles (such as interviewing other metallurgists on the problem and comparing macrophotographs of well-preserved identical punch marks on paintings by different artists) might have avoided some of the criticisms that are sure to come. As it now stands, some readers will continue to protest that the tools were cast even after reading what Skaug has to say. In the opinion of this reviewer, the argument for engraving over casting should have been made earlier in the book.

For a book that is already expensive, it is unfortunate that the photographic illustrations are not of higher quality. The images are sharp, but the plates have a graininess and flat quality that is directly the result of the type of screen used. Furthermore, an English editor could have culled the unfortunate typographical errors and occasional awkward phrasing that mar this otherwise lucidly written and fascinating book.

In these two volumes we are presented with a sumptous feast of information and new ideas that should be a rich source for scholars in years hence. Whereas in Skaug's book attention has focused on the individual punch shapes, future avenues of research could emphasize halo design and subjective areas such as the execution of tooling, which could perhaps be studied as a means of distinguishing various hands in a shop. Skaug discusses only briefly the incised, tooled, and pastiglia halo designs of the 13th century, but this topic could be an important one for an enterprising student, since it presaged the full halo tooling innovation of Simone Martini in 1319 and the influence on his colleagues and their followers.

Norman E.MullerThe Art Museum, Princeton University, Princeton, N.J. 08544JULIE L.SLOAN. CONSERVATION OF STAINED GLASS IN AMERICA: A MANUAL FOR STUDIOS AND CARETAKERS. Brewster, N.Y.: Art in Architecture Press, 1995. 225 pages, softcover, $24.95. ISBN 1-884966-01-2.

This book is meant to give those responsible for stained glass an overview of the field and to provide those working in it some guidance on specific conservation materials and techniques. Julie Sloan is an engaging writer and an able researcher. She is an adjunct assistant professor of historic preservation at Columbia University. After graduating from that program, she worked briefly for a stained glass studio in New York City before opening her consulting practice. She has taught stained glass conservation at Columbia and in seminars around the country. As a preservationist and stained glass consultant, Sloan has worked with many stained glass conservators who have shared their expertise and experience with her. In her numerous published articles—sections of the book first appeared in various stained glass magazines—she has combined this technical information with current preservation philosophy focusing on making the preservation field more accessible to the stained glass field and vice versa. The book has two parts: “Theory and Practice” and “Materials and Processes.” In part 1 Sloan is most clearly in her element, with chapters entitled: Definition of Terms; Conservation Philosophy; The Technical History of Stained Glass and Restoration; and Condition Analysis and Contracting. The book's strength lies in the author's overview of the history of stained glass and stained glass conservation—how it evolved, its present state, and how much more there is to achieve. Stained glass conservation in America is in its infancy, though the field has a strong tradition of restoration and repair. Just as in decades past most paintings conservators were painters, virtually all stained glass conservators began as artists and craftspeople who then became involved in conservation. As more and more craftspeople and studios have been exposed to conservation—Sloan has contributed to that through her writing—conservation is being understood and appreciated for what it has to offer, becoming a focus of many studios' business.

The Materials and Processes sections contain much useful, practical information covering: Glass; Cames, Putty, and Structure; Glass Paint; Cleaning; Documentation; and Protective Glazing. It soon becomes apparent that the future of stained glass conservation entails educating craftspeople not only in conservation philosophy but also in science, and that much basic research needs to be done in the materials commonly used and appropriate solutions found to problems, some of which are just beginning to be defined, much less solved.

Stained glass conservation must be held to the same standards as the wider field of conservation. For this reason, one would expect to find concise and definitive explanations of glass chemistry, vitreous paints, glass enamels, UV levels, and other issues. However, these discussions are disappointingly imprecise and confusing, at times containing speculation rather than research, even though much of the information is readily available. One example involves the discussion of the various types of glass paint. Sloan writes that they are distinguished by the “amount” of flux in the paint, when, more accurately, they are distinguished by the composition of the flux—because the composition determines the firing temperature, the transparency, and the resistance to acids, alkalis, and the weather. A more well-grounded approach to materials and conservation science would seem to be essential, especially since the book hopes to reach students and conservators.

While the book does not aim to be scholarly, it nevertheless suffers when it refers to “studies” that have arrived at various important conclusions or when it provides information that is not well known in the field, yet fails to cite specific studies or give sources, leaving readers with only the author's interpretation of them. This absence of documentation is especially troublesome in discussions of potential problems with widely used materials. For example, “some research in Europe” is cited in one of several vague references to potential problems with linseed oil putty and vitreous paint and lead. However, while this matter obviously warrants more study, linseed oil putty has been used successfully for centuries, will continue to be used, and is recommended in the book. This general lack of citations will significantly limit the book's usefulness for conservators, who must be able to see the research for themselves and verify data in order to use the research and expand upon it.

Many working methods recommended in the book could be debated, but their appropriateness would vary from conservator to conservator and project to project. As Sloan points out, there are a few things that should never be done (e.g., refiring historic glass or cleaning with hydrofluoric acid). Many of the other particulars of a project must be puzzled out with the window in front of you and experience behind you. Different techniques are presented that are currently in use and unique to stained glass conservation.

Students would have benefited from explanations of the thought processes behind the techniques. For example, while it is said that when gluing one should tape the unpainted side of a piece of glass first, it is never said why one would do so (the reason: the tape might affect the paint, pulling it off or putting it under dangerous stress). With this explanation left unsaid, the student must guess at when and if it would be all right to use tape on the painted side.

The chapter on glass paint discusses the very serious problems inherent in American painted glass. Readers will be dismayed to find that many windows have lost and continue to lose their vitreous paint. Sloan points out that much is not known in this area, and since the research has not been done, little can be said definitively. The mention of “cold” (unfired) paint is important, since as the author notes this paint was often removed before it was realized that it belonged on a window.

Unfortunately, the references to silver stain, a very important component of painting on glass, give the reader a wrong impression of its properties. Silver stain is fundamentally different from vitreous paint in that it does not “fuse” onto the glass substrate but forms a colloidal dispersion within the substrate during firing. Several factors determine how intense the color will be: the composition of the glass, the composition of the silver stain, the temperature during the firing. But what silver stain fires in, fires in as completely as possible due to an exchange of ions. “Incomplete firing [of silver stain] does not seem to affect longevity,” says Sloan, because whatever ion exchange takes place is always within the matrix of the glass substrate, which also explains why the silver stain does not “flake.” If there is a bluish metaling in reflected light, it is a result of overfiring, not underfiring.

The section on condition analysis and contracting will be of interest to owners, conservators, studios, and consultants, as it outlines different steps to be taken before commencing a restoration project. It is balanced and reasoned and will help all these individuals through a complex process. However, the author's blanket statement that “stained glass craftspeople are also not generally recommended as specification writers” is puzzling since, as already noted, virtually everyone who would be qualified to write specifications comes to the task as a craftsperson.

The chapter on protective glazing is useful for its discussion of why one would consider using it, where it is not needed, and the materials in current use. As the author notes, the installation of protective glazing has become an ample source of income for some studios, influencing its installation in many settings where it is not strictly needed and in some instances were it is actually doing harm. Sloan provides some help in sorting through the pros and cons. This area is of great interest to the field, and while consensus is emerging (venting to the interior being preferable in many circumstances) there is still much research to be done before useful guidelines can be determined. Again, references would have been very helpful in enabling the reader to follow up on the information given.

The quality of the illustrations is uneven; it is not always possible to see what the caption is pointing out. The fault is probably more in the printing than in the photographs themselves.

The discussion of documentation should spur owners to record their windows now, for a variety of good reasons, one of which is to have a record of the window in case of future loss or damage. It would have been interesting to include a discussion of the ethical questions raised by reproductions.

The bibliography is very selective. Any serious student of stained glass conservation must also check other sources for current literature. The most important reference for conservators is The Conservation of Glass, by Newton and Davison (Butterworths, 1989). Another uneven but useful source that is not included in the bibliography is the SGAA Reference and Technical Manual (2d ed., Lee's Summit, Mo.: Stained Glass Association of America, 1992). It contains information on all aspects of stained glass written by a wide range of people in the industry.

It is rare that one book can address all the issues in a given field with consistent authority. One must consult a variety of sources for different perspectives and areas of expertise. The imprecise technical information and insufficiency of footnotes significantly limit this book's usefulness as a reference tool for conservators. However, it will be a help to owners who need more information on how to understand the care of their windows in general terms and for those who are beginning to learn something about stained glass conservation and need some perspective on its development. The author offers many insightful observations as she presents concise overviews of the field, introducing the reader to the craft and explaining many of the issues that must be confronted and resolved during treatment.

Mary ClerkinHigginsClerkin Higgins Stained Glass, Inc., 265 Cabrini Blvd., #1C, New York, N.Y. 10040HENRYWILHELM, WITH CAROLBROWER. THE PERMANENCE AND CARE OF COLOR PHOTOGRAPHS: TRADITIONAL AND DIGITAL COLOR PRINTS, COLOR NEGATIVES, SLIDES, AND MOTION PICTURESGrinnell, Iowa: Preservation Publishing Co., 1993. 744 pages. ISBN 0-911515-00-3.

The Permanence and Care of Color Photographs: Traditional and Digital Color Prints, Color Negatives, Slides, and Motion Pictures has already received some 60 favorable reviews in the two years since its publication, so it would seem that this reviewer's words are unnecessary. In addition, I count the authors both as professional colleagues and personal friends, a situation that can make it more difficult to review the work dispassionately. Nonetheless, I welcome the opportunity to speak about this extraordinary book.

With 20 years of intensive research behind it and at more than 700 pages in length, The Permanence and Care of Color Photographs reads more like an encyclopedia than a general textbook on the care of color photographs. It is not just about color photography. This book is really the definitive reference book on the preservation of 20th-century photographic materials, and it tells an intriguing story. It does not flinch from identifying the aging characteristics of specific brand names, and in doing so, Wilhelm has helped the photographic community set higher standards for image permanence. The book instructs the reader on the urgency and vital need for cold storage as the primary means for preserving photographic records. This book is also important because it will greatly serve future historians as they examine the transitional years from the dominance of photography based on silver halide chemistry to the emergence and eventual succession of digital electronic imaging. One can cite Towler's The Silver Sunbeam or Hardwich's A Manual of Photographic Chemistry, or perhaps Estabrooke's The Ferrotype and How to Make It as 19th-century publications that help us reconstruct and understand photography as it was practiced in that era. The Permanence and Care of Color Photographs will stand out analogously as a guide to 20th-century photography in the decades to come.

In many areas, Wilhelm's book reveals timely and current information that will soon become obsolete because the processes themselves will become obsolete. However, the book is a showcase for Wilhelm's extensive evaluation of light fading and dark fading and staining characteristics of modern photographic media. Moreover, it accurately reflects the current state of photographic conservation: our beliefs, our guidelines, our specifications, and the characteristics of the modern materials we must now preserve for future generations. For example, Wilhelm introduces the reader to several of the American National Standards Institute (ANSI) photographic specifications. In chapter 16, “Storage Environment: Relative Humidity, Temperature, Air Pollution, Dust, and Fungus,” Wilhelm reports the specifications of ANSI IT9.11-1991. This standard concerns relative humidity and temperature specifications for film storage, and it had undergone a major revision that was published in 1991. In citing this standard, Wilhelm's book was clearly up to date at the time of publication in 1993, but this ANSI standard has already undergone further major revisions. The quick revision schedule reflects an evolving understanding by conservation professionals of environmental conditions and how they affect photographs in terms of both physical and chemical stability. The changing guidelines also reflect what is slowly becoming apparent to many photographic experts: the tremendous need for cold storage. Thus, while some information in this book has already been affected by advances in knowledge and developments in technology, as it will continue to be, Wilhelm's recommendations for preservation are well balanced and meticulously presented. His reasoned approach to such technically complex subject matter will ensure that this book remains a classic textbook on the care of photographs.

One particular strength of Wilhelm's book is its ample documentation, both in text and photographs, of numerous institutions' approaches to cold storage. I know of no other book that informs the reader so thoroughly about this important subject. Contributing author Carol Brower is equally meticulous in chapter 12, “The Handling, Presentation, and Conservation Matting of Photographs.” There is more insight given in this one chapter than in many books dedicated entirely to the subject of framing and matting techniques. Complementing chapter 12 is chapter 13, “Composition, pH, Testing, and Light Fading Stability of Mount Boards and Other Paper Products Used with Photographs.” Included in chapter 13 is a fascinating photographic essay on the Strathmore Paper Company's mill manufacturing process for 4-ply museum mount board.

The organization of a book that is filled with so much information is not likely to satisfy everyone. Some chapters in Wilhelm's book do not follow a progressive route. They can be read in any sequence, for this is not a book that needs to be comprehended in a linear fashion. Wilhelm's book and the research it encompasses form a work of monumental size and follow the philosophy of telling the reader something, telling the reader again, and then telling the reader what he has been told. The purposeful repetition of important themes such as the effects of light, heat, and humidity on image permanence and the need for cold storage helps convey what Wilhelm and Brower know to be essential information for a full understanding of photographic materials, their heritage, and their preservation.

This book is highly recommended for anyone who is serious about photography. Amateur and professional photographers will benefit from an improved knowledge of the materials and ways their finished works age over time. Private collectors, archivists, curators, and conservators entrusted with the preservation of photographic collections will benefit by learning about the importance of the storage and exhibition environment as well as the proper handling and exhibition of photographs.

Mark H.McCormick-GoodhartConservation Analytical Laboratory, Smithsonian Institution, Washington, D.C. 20560


In the article by M. A. Becker, P. Willman, and N. C. Tuross, “The U.S. First Ladies gowns: A biochemical study of silk preservation” (JAIC 34[1995]:141–52), the title given in the author's bio for Polly Willman is incorrect. She is the senior conservator of costumes at the National Museum of American History.

Copyright © 1996 American Institute for Conservation of Historic and Artistic Works